Gas sensor devices for measuring the amount of gas are used in various technical fields. Included in the gas sensor devices in the field of the automobiles are humidity sensors which measure the humidity in internal combustion engines to achieve the optimal operation of the internal combustion engines and the concentration sensors which measure the concentration of the fuel in the gas intake passages of the internal combustion engines. These gas sensor devices are also used in the internal combustion engines and the fuel cells that use hydrogen as the fuel of the engines.
The gas sensor devices used in the gas intake passages of the internal combustion engines require, for example, the high degree of accuracy, the stain resistance, the impact resistance and the heat resistance. Meanwhile, the recent internal combustion engines are provided with a variable valve mechanism that changes the timing to open and close the intake and exhaust valves of the combustion chamber to thereby improve the fuel efficiency. The internal combustion engines provided with such a variable valve mechanism induces intensive changes of the flow speed and the pressure of the intake gas in the gas intake passages thereof. In addition, the condition of the intake gas varies depending on the number of cylinders, and the length and the shape of the gas intake passage of the internal combustion engine. Thus, highly accurate measurement of the intake gas in such an environment of the gas intake passage is required.
PTL 1 and 2 disclose a known technique that is arranged to correspond to the change of the flow speed and the pressure of the intake gas in a gas intake passage. PTL 1 (JP 2013-36852 A) as a prior art includes a gas sensor (concentration sensor) that outputs an output value corresponding to the specific component concentration, which is the concentration of a specific gas component contained in gas, and a pressure sensor that measures the pressure of the gas, wherein a provisional specific component concentration is calculated from a concentration sensor value and a pressure sensor value, and the provisional specific component concentration is corrected by using a functional correction value (see Abstract). The pressure sensor and the concentration sensor, or an oxygen sensor, in PTL 1 are separately disposed at an upstream side and a downstream side (in the flow direction of the intake gas), respectively, in the gas intake pipe (gas intake passage) of the internal combustion engine (refer to paragraph 0029). PTL 2 (JP 2010-151795 A) is a prior art that includes an environmental sensor element such as a pressure sensor element, a humidity sensor element, a temperature sensor element and the like, and at least one of these elements is disposed in a measuring chamber, which is positioned farther from a pipe wall than from a bypass route, to thereby reduce the influence of the gas flow and the heat of the pipe wall (refer to paragraph 0015-0027).